Self-stabilizing rod penetrators



P 1959 s. WASSERMAN ET AL 3,464,356

SELF-STABILIZING ROD BENETRATORS Filed D96. 28, 1967 INVENTORS SAUL WASSERMAN ROBERT SALZMAN WALTER O'KEEFE United States Patent 3,464,356 SELF-STABILIZING ROD PENETRATORS Saul Wasser'rnan, Rockaway, N.J., Robert Salzman,

Arlington, Va., and Walter C. OKeefe, Landing, N.J., assignors to the United States of America as represented by the Secretary of the Army Filed Dec. 28, 1967, Ser. N 0. 694,188 Int. Cl. F42b 25/08 US. Cl. 102-67 3 Claims ABSTRACT OF THE DISCLOSURE A rod for penetrating enemy target which includes a collapsible flared section on its rearward end, for permitting denser packing and aerodynamic stabilizatlon.

The invention described herein may be manufactured, used, and licensed by or for the government for governmental purposes without the payment to use of any royalty thereon.

The invention relates to a rod penetrator and more particularly to a rod penetrator having a collapsible flared section on its rearward end.

Rods of high length/diameter ratios have been found to be excellent penetrators. To eflect penetration, the rods must contact their targets headon, which requires precise stability in flight.

Stability in flight may be achieved gyroscopically or aerodynamically the latter presenting fewer problems due to the elimination of any elaborate mechanisms needed for spin-up.

Aerodynamic stabilization of rods by means of a noncollapsible flared section on the rearward end thereof poses two major disadvantages, namely, (1) high drag and (2) low packing density. The flared section offers high drag resistance and quickly acts to reduce the velocity of the rod. This is not a serious problem, however, where distances of intercept are short or air densities are relatively low. In these two instances, the velocity of the rod will not decay substantially below that required to effect a kill.

The second disadvantage, that of low packing density, is of major importance since the number of lethal mechanisms capable of being carried by a warhead is directly related to hit prob ability.

One method of packing rods having flared sections would be to place the rods in a nose-to tail fashion, thus, while desirably increasing the density of packing, would suffer the disadvantage of having one-half the rods launched backwards with obvious stability or aerodynamic drawbacks.

It is therefore an object of the present invention to provide a rod penetrator having a flared section on its rearward end for aerodynamic stabilization.

Another object is the provision of a rod penetrator having a collapsible flared section on its rearward end permitting denser packing than heretofore achieved.

The above objects as well as others together with benefits and advantages of the invention will be apparent upon reference to the detailed description set forth hereto wherein:

FIG. 1 is a perspective view with parts broken away, of the invention in its open position.

3,464,356 Patented Sept. 2, 1969 FIG. 2 is a perspective view with parts broken away, of the invention in its closed position.

FIG. 3 shows a pluralty of inventive devices as placed in a warhead.

FIG. 4 shows an enlarged view of a plurality of inventive devices.

As seen in the drawings, a rod penetrator 10 has a volute spring 12 secured to one end thereof. The spring is secured at its closed end 12' to the rear of the rod penetrator 10 by the use of an epoxy resin. The spring 12 is covered by an elastic membrane 14 also secured by epoxy to the rod 10. When the spring 12 is contracted, the rod 10 has the configuration as illustrated in FIG. 2. In this closed position the flared section 16 is contracted to the diameter of the solid cylindrical rod body portion 18 of rod penetrator 10 thereby enabling easy packing of the rod penetrators 10 into a dense matrix 20 (FIGS. 3 and 4). When the rods are packed in a matrix bundle 20, the spring 12 of each rod 10 is held in compressive restraint by the adjacent rods, however when this restraining force is released by the breaking up of the matrix bundle 20, the spring 12 expands, as shown in FIG. 1. The volute spring 12 has the unique property of expanding in width as well as length upon release. This expansion provides a supporting skeleton framework for the membrane 14 which is attached to the ends of the spring and which, upon the springs expansion, stretches to its full length and width. The smooth surface of the membrane produces the outer assemblance of the frusto-conical configuration of aerodynamic contour, as shown in FIG. 1.

As an alternate method of construction the turn of the volute spring in expansion could be tight enough to provide a continuous aerodynamic surface without the need of a membrane.

In packing the matrix bundle 20 (FIG. 4) into a warhead 22 the fiared section 16 of each rod penetrator would have to be held in such as way as to prevent the spring 12 from unwinding. Once the particular rod penetrator has been inserted into the matrix bundle 20 then each adjacent rod penetrator would prevent of its spring unwinding.

We claim:

1. A rod penetrator comprising:

a solid cylindrical rod,

a volute spring having an open end and a closed end and secured at its closed end to a rearward portion of said rod,

said volute spring being expandable from a constrained position in which it is cylindrical and of substantially the same diameter as said rod to an unconstrained position in which it expands axially and radially thereby to assume a frusto-conical configuration in which the forward base of the spring is contiguous with the rearward end of said rod and is smaller in diameter than said rod and the rearward base of the spring is larger in diameter than said rod, to maintain aerodynamic stability in flight of said rod penetrator.

2. A rod penetrator of the type described in claim 1 having an elastic membrane covering said volute spring.

3. In combination with a warhead having a matrix of rod penetrators, each rod penetrator including:

a solid cylindrical rod,

a volute spring having an open end and a closed end, References Cited an elastic membrane covering said volute spring, UNITED STATES PATENTS said volute spring secured at its closed end to a rear- 1 305 967 6/1919 Hawks 102 67 ward portion of said rod and held in a constrained 2368258 1/1945 g position in which it is cylindrical and of substantially 5 2671398 3/1954 Peck the same diameter as said rod by the adjacent rod 3:081:703 3/1963 Kamp et a1 penetrators in said matrix whereby upon release of 3,114,315 12/1963 Trump 102 4 said matrix said rod penetrator will separate from said matrix and said volute spring will expand axially FOREIGN PATENTS and radially thereby to assume a frusto-conical con- 10 550,001 12/1942 Great Britainfiguration in which the forward base of the spring is contiguous with the rearward end of said rod and BENJAMIN BORCHELT Primary Exammer is smaller in diameter than said rod and the rearward 1. FOX, Assistant Examiner base of the spring is larger in diameter than said rod, 15

to maintain aerodynamic stability in flight of said rod CL penetrator. 4 1024 

